Most bats prefer to dine on pests such as mosquitoes, moths and other creatures that are active at night. “There are nine species of bats in Delaware and they’re insectivores,” she said. “They just don’t have the same kind of lifestyle we do. They’re nocturnal, so most people see them only at dawn or dusk.

“I’ve had people tell me they see bats flying around here or there, but they’re actually foraging everywhere.”

To observe bats, look for them around dawn or dusk near buildings where they’re known to nest.

“It’s really cool, especially when there are a lot of them,” Niederriter said. “But even if there are only a few, it’s still pretty cool.”

They only come out at night

This time of the year is particularly important for the bat population, Niederriter said. They have come out of hibernation, and pregnant females are ready to give birth. But females create maternity colonies in barns, garages and attics, places where they’re usually not welcome.

DNREC has been urging homeowners and farmers to install devices such as netting or cones to keep bats away, but some bats get in and out through very small openings.

In a press advisory, DNREC spokesman Michael Globetti notes these measures should be in place now, the time around when most births occur. The danger is that after pups are born, any device to keep foraging females from returning to the colony will mean the babies starve to death.

Females bear only one or two pups per year, and the newborns are very fragile, Niederriter said. As the males tend to be solitary, the females can’t count on them for any help in raising their young, she added.

“The females will want it to be really hot, between 90 and 100 degrees, because the pups are born without fur,” she said. “They look like pink mice.

“Without fur, they’re very helpless, and they get cold very easily, which is why they prefer higher temperatures.”

Wildlife biologists advise that if people haven’t installed bat exclusion devices by now, it’s better to accept the possibility their property may become home to a maternity colony.

“Female bats are very good mothers,” she said. “They’ll throw all their resources into their pups, and they’ll get frantic if they can’t get to them. They’ll try to get inside any way they can.

“And the pups will be desperate to get out,” she added. “They’ll try to crawl into people’s living spaces.”

Allowing the newborns to die creates another set of problems.

“You don’t want dead bats in your home,” Niederriter said.

Voracious eaters

On the wing -- they’re the Earth’s only flying mammals -- bats can eat up to half their body weight in insects each night. The come in many sizes, and depending on the species, weigh between seven-hundredths of an ounce to a little more than two pounds.

One enduring bat myth is they swoop out of the dark, attacking people and getting tangled in their hair. However, bats don’t care about us humans, they’re simply looking for their daily meal and we tend to get in the way.

“They don’t want to mess with us,” Niederriter said. “We’re pretty big compared to them, and they know they don’t stand a chance.”

But humans do get in the way when mosquito-hunting bats target the blood-suckers congregating around us. Bats use echolocation -- their ability to send out and receive sound waves -- to navigate through the air and to target food.

“Because all those bugs are flying around, the bats will tune into that echolocation,” Niederriter said. “They do sometimes sweep down on people, but they know exactly where we are.”

In the past few years DNREC biologists and their counterparts in other states have spotted a deadly disease among bat populations.

White nose syndrome is a fungus found in hibernating bats. It does not affect humans, but is almost always fatal to bats. White nose syndrome was found about four years ago in hibernating bats at Fort Delaware; three entire colonies, mostly little brown bats, have been wiped out, Niederriter said.

DNREC has a volunteer program for people interested in counting bat populations, especially as a way to measure the impact of white nose syndrome in the state.